1541 disk drive - "File Not Found"

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BennehBoy
Posts: 219
Joined: Sat Apr 24, 2021 12:35 pm

1541 disk drive - "File Not Found"

Post by BennehBoy »

I picked up a 1541 on ebay, it power ups fine and receives commands but will not read any files or a directory.

I am getting this issue ->

I've tested the resistance of the r/w & erase heads and they are exactly what they should be.

The drive faceplate has a repaired crack so I think it's been dropped on that end at some point and probably taken something out of whack mechanically.

A software drive speed check/alignment requires that the drive can actually read and write OK and it's so far out I think that this just errors. There's a timing disk on the underside of the spindle motor but I can't find any information about how to reliably time the drive using this - does anyone have any info?

For info, I have a 2nd working drive, exact same revision & floppy mechanism (ALPS), the PCB from this new drive happily runs the mechanism in the other, the mechanism from this drive results in the same problem when used with the PCB from the 2nd.

So I know it's not an electronics issue, and the PSU's are fine in both drives.

Probably need to brush up my googling technique!

PS I forgot to say that the head has been thoroughly cleaned with IPA, not just the actual head but all around to remove any accumulated magnetic detritus.
BennehBoy
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Re: 1541 disk drive - "File Not Found"

Post by BennehBoy »

Found this ->

Spindle speed is fine, but I get no head alignment data at all no matter how I adjust the stepper alignment, so I'm disinclined to believe the resistance of the heads being the only factor here :/
BennehBoy
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Re: 1541 disk drive - "File Not Found"

Post by BennehBoy »

So sometimes the simplest things cause the biggest issues!

Looks like whoever had this drive apart/fixed the crack, reassembled it incorrectly, the eject mechanism was sat on top instaed of under the guides on the faceplate, this meant the head wasn't getting any pressure from the pressure pad above == no signal.

Nice easy fix!
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Re: 1541 disk drive - "File Not Found"

Post by exxos »

:bravo: :goodpost:
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
BennehBoy
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Re: 1541 disk drive - "File Not Found"

Post by BennehBoy »

Cheers, very chuffed as I got this thing a lot cheaper than they normally go for.

I've just done a device ID mod so I'll post some pics of that tomorrow.

I'll then be installing a jiffydos eprom (and adapter), and also a dolphin dos 2 parallel board (that thing is lightning fast).
BennehBoy
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Re: 1541 disk drive - "File Not Found"

Post by BennehBoy »

I own a 1541 Ultimate II+, so in order that I can use my real 1541 at the same time it's nice to be able to switch the device ID. On a 64 a 1541 can have an ID of 8,9,10, or 11. Unfortunately this is not a factory switchable option but requires some modification to the drive.

The ID can be set in a few ways, one of which includes lifting legs on IC's - I didn't really want to do that so opted to permanently wire in a toggle switch. There are 2 jumpers on the drive board that combined in binary set the ID (inverse binary). They are both closed from factory, and the one closest to the drive front (on my short board drive) needs cutting to make an ID of 9, factory ID is 8.

The pads are in the centre of this photo

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Next I soldered some solid core wire (probably would've been better with braided core) to the pads and ran these to a SPST ON/OFF toggle switch I'd panel mounted to the rear of the 1541 upper case.

Blurry pic follows...

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The switch and a hastily printed label - I've also drilled out a hole to panel mount a dolphin dos enable/disable switch

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BennehBoy
Posts: 219
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Re: 1541 disk drive - "File Not Found"

Post by BennehBoy »

The 1541 is notoriously slow, there are a few options to speed things up, the faster things get the less compatibility there is so it's good to have a few options....

My C64 has a quad kernel rom fitted, with this I can cycle between a stock kernel, one with jiffydos, a jiffydos/dolphin dos hybrid, and a full dolphin dos kernel.

* Jiffydos is a c64/1541 set of replacement roms that can give up to 25X speed increase.

* JiffyDolphin is the same but with the kb shortcuts from Dolphin Dos

* Dolphin Dos is a c64/1541 rom, and parallel hardware upgrade and is by far the fastest option - but a lot of software fastloaders for game disks don't work with it so it needs the ability to be disabled.

Anyhow, first things first I wanted to add the jiffydos rom into this new drive.

I had PCBWay make up 40 maskrom to eprom adapter boards so put one of those together first - the adapter allows 8, 16 & 32kb eproms to be used, I went with an 8kb rom - so the resistors on the other address lines probably weren't required, but I fitted them anyway.

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Next I burned the rom in my TL866

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Finally removed the stock rom and inserted the adapter. The board will probably get an IPA wash before long, it's a bit mucky.

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derkom
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Re: 1541 disk drive - "File Not Found"

Post by derkom »

Hey, @BennehBoy, when you include pictures in a post, please use the forum's attachment function (you can generally just drag a picture onto the text field in the editor) and then "Place inline" from the attachments tab. Externally hosted images have a habit of losing their hosting.

I have rehosted images in your posts.

Thanks!
BennehBoy
Posts: 219
Joined: Sat Apr 24, 2021 12:35 pm

Re: 1541 disk drive - "File Not Found"

Post by BennehBoy »

After testing Jiffydos and being happy that it was working, I then decided to go to the next level and fit my dolphin dos 2 copy (these still get sold on ebay).

Step 1 is to pull the 6502 and one of the VIAs

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Next these are inserted into the dolphin dos board

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Then the board goes into the empty VIA & CPU sockets which I didn't take a pic of.


A small slot needs to be cut in the case for the parallel cable to exit through, here I mark it up, and then you can see the cut case

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And finally all back together nice and neat.

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When the SPST ON/ON toggle switches arrive I'll add this into the empty switch hole and wire back to the green jumper headers on the dolphin dos board.

I'll do some timings later to show the speed differences.
BennehBoy
Posts: 219
Joined: Sat Apr 24, 2021 12:35 pm

Re: 1541 disk drive - "File Not Found"

Post by BennehBoy »

derkom wrote: Wed Jun 02, 2021 5:31 pm Hey, @BennehBoy, when you include pictures in a post, please use the forum's attachment function (you can generally just drag a picture onto the text field in the editor) and then "Place inline" from the attachments tab. Externally hosted images have a habit of losing their hosting.

I have rehosted images in your posts.

Thanks!
Ah sorry, I've done it this way for years, my bad.
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